13 October 2013

I often get questions asking about DMX and how it works so I thought it might be useful to recycle my presentation about DMX from the 2012 Academy that talks about the basics of the DMX protocol.

What can DMX do?
• DMX is simple – it is designed to control
devices, usually lights
• This may also mean just turning on and off a device
• Work with desperate devices and software applications

Where did “DMX” Come From?
• DMX was designed as a public standard to allow hardware and software vendors to all be able to
design inter-operation devices
• Designed in the early 90’s
• Developed by USITT – United States Institute for Theatre Technology
• Designed to be very reliable (but not guaranteed – no error checking)

What is DMX?
• DMX is a protocol
• DMX is a public standard
- E1.11 (ANSI)
- Just a set of rules
• DMX runs “over” other protocols or wiring systems

08 October 2013

After reading, and watching several videos on your site,
I would like to test an RGB Pixel setup (100 lights per string, using your
tinypix controllers). I am using LOR S3 Advanced software, and would like you
to verify what I will need (to make sure I don't miss anything).

Currently, I am just using the inexpensive Light-o-Rama
USB485 dongle, at 500K (network speed), and it works great - will that work, or
do I need to use one of your dongles, and if so which one - Ultimately, I will
be using this for 12 arches (50 pixels each).

I know I need a 100 light pixel string, 1-tinypix,
programming cable, and power supply - for the testing of the single string, I
will just use one I have on hand). other then the possible dongle, is there
anything else I will need???

So let's break down this issue - Phill would like to make pixel arches and he has indicated that he needs 12 of them at 50 pixels each. My first question would be - what type of RGB pixel is being used here? My guess is pixel strip given that the number is 50 pixels and pixel strip commonly comes in 16' lengths that contain 50 pixels (150 DMX channels), so we'll go with that given that pixel strip is a reasonable choice for pixel arches.

The next question I'd have is - what type of interface is going to be used here to get the sequencing data to the pixel controller? 50 pixels * 3 DMX channels (Red, Green, Blue) * 12 = 1,800 DMX channels - so that's a fair number of pixels and is comprised of 3 DMX universes (actually 4 because you would likely put 3 arches of 150 pixels each, within a single DMX universe of 512 channels.) So, I think an RS-485 interface is out of the question here - the customer is going to need to go E1.31 for output of that much data.

So, to answer Phills question about LOR - yes, you'd need at a minimum LOR S3 advanced to get enough output and E1.31 support. Phill would run the LOR network separately of the DMX network, so Phill's LOR settings really don't matter here since they don't impact the DMX E1.31 network.

Phill mentions needing a "100 light pixel string" which isn't correct based on my assessment that he has chosen RGB pixel strip, so maybe he is referring to 8mm pixel nodes? If that is the case, usually 8mm pixel nodes would be a bad choice for this design - they don't mount well, you have to get them pointed in the right direction and they have less light output than the 5050 RGB chips in RGB strip - so we are going to just forget the 100 light pixel string reference and again assume he needs RGB pixel strip.

Phill also mentions needing a TinyPix - I can't say if that is the case because I know nothing about the distances involved. A centralized controller is great, something like the SanDevices E68x or the J1Sys controllers but they do have limits on distances you can place elements from the controller - yea, you can use null/ghost pixels to span longer distances but I'm not sure if we are talking 2 acres or a 5,000 sq/ft yard. In the 2 acre, now a distributed pixel controller like the TinyPix really makes sense, if you have them all very close to each other, a centralized controller makes sense. Now please note that the TinyPix is RS-485 based and thus would require "dongles" for output of each DMX universe as where the centralized controllers would require an Ethernet feed from the show computer.

So, to completely answer a question such as those posed by Phill, we need to know other relevant data such as: